U.S. Pat. No. 5,733,616 issued to Janicki et al. describes injection molded containers made from polymer-modified asphalt for containing raw or processed, e.g., air-blown, asphalt. Molten asphalt is poured into the molded containers at a pouring temperature of about 300.degree. F. Upon solidification of the asphalt by cooling, the filled containers may be stacked for storage and/or transported to the end use location. Typically, the asphalt filled containers are added to a gas-fired asphalt melting kettle for remelting at approximately 450.degree. F.-550.degree. F., preferably less than 530.degree. F. Accordingly, the container is consumable in that the container is melted or solubilized in the kettle for consumption in the end use asphalt application, such as roofing or road paving. The container is molded from a polymer-modified asphalt material which contains by weight about 40% to about 90% asphalt and about 10% to 60% of a polymer material. In the melting kettle, the polymer melts along with the asphalt, and some of the polymer collects on the upper surface of the molten asphalt prior to dissolution to form a skim which significantly reduces fuming of the molten asphalt.
A problem with the molded containers, however, is that they are susceptible to breakage due to impacts during transportation or other rough handling by equipment or workers. While certain advances have been made in making these containers tough and impact-resistant, such rough handling can cause cracks, splits, or holes to appear in the container. Such apertures have rendered the containers unusable since the molten asphalt poured into the containers would leak from the containers. Certain areas of the containers are more susceptible to damage than other areas. These areas include the top center of the longer side, near the injection gates due to higher temperatures, and at the comers. Short shots, that is, containers resulting from molds that are not completely filled with molding material, are especially susceptible to damage. In the past, such damaged containers have been disposed of or ground for compound reuse. These solutions to the problem unnecessarily reduce the efficiency of the container manufacturing process, increase manufacturing costs, and may consume limited landfill or incinerator capacity.
In the past, it has been suggested to repair the damaged containers by applying fiber-reinforced adhesive "duct" tape to the cracks, splits, or holes, but this remedy was found to be unsatisfactory. The glass or textile fiber reinforcements did not melt or solubilize in the remelt kettle. The fibers had a tendency to form undesired clods which were subsequently introduced directly into the asphalt customer's end use.
U.S. Pat. No. 4,692,195 to Allen describes a method for repairing and reinforcing a torn plastic tote. The method entails preparing the tears for plastic welding, welding the tears with a compatible plastic material, and providing a band of plastic reinforcing material around the upstanding sidewalls of the tote and securing the band to the sidewalls. The totes are repaired rather than disposed of. The Allen method does not address the particular requirements of asphalt processing. It is believed that if a weld similar to that shown in the Allen patent were attempted on a polymer-modified asphalt-based container, the weld would be too weak and would fail upon addition of molten asphalt to the welded container.
Accordingly, there continues to be a need for a cost-effective solution to the problem of damaged polymer-modified asphalt-based containers which does not detract from the quality of the asphalt customer's end use application.